Air operated hydraulic pump



Sept. 9, 1969 F. A. NUGIER AIR OPERATED HYDRAULIC PUMP 2 Sheets-Sheet 1 54 Z6 Filed Oct. 16, 1967 INVENTOR.

PEA/V675 ,4. A/Z/G/EE BY P 9, 1969 F- A. wuslfi 3,465,686 in AIR OPERATED HYDRAULIC PUMP Filed Oct. 16, 1967 2 Sheets-Sheet 2 fiwi T INVENTOR. FZ/M/C/S A. MUG/6K United States Patent 3,465,686 AIR OPERATED HYDRAULIC PUMP Francis A. Nugier, 547 Capala Drive, Pacific Palisades, Calif. 90272 Filed Oct. 16, 1967, Ser. No. 675,658 Int. Cl. F0411 17/00; F011 25/08 US. Cl. 103-51 11 Claims ABSTRACT OF THE DISCLOSURE An air operated hydraulic pump and shuttled valve as sembly therefor. An air piston mounted within a cylinder reciprocates back and forth under air pressure to operate an oil plunger. Reciprocation of the piston is controlled by a shuttle valve assembly which causes air to be alternately supplied to opposite sides of the piston. Differential air pressure and magnets in the shuttle valve assembly cause the shuttle thereof to positively move to one position or another.

The present invention relates to pumps and more particularly to air operated hydraulic pumps and an improved shuttle valve assembly used in combination therewith.

Various types of hydraulic pumps and valves for controlling the operation thereof have been devised. A typical hydraulic pump includes one or more plunger pumps operated by a piston and cylinder assembly to which a fluid, such as air, is supplied to move the piston. Generally a shuttle valve is coupled with the piston and cylinder assembly and includes a spool or shuttle which re ciprocates to appropriately control airflow thereto. The operation of the shuttle valve must be positive, that is, it must operate fully from side to side and not stop in an intermediate position which would cause stalling. Typical shuttle valve assemblies have employed arrangements including detents, springs, or the like to ensure positive operation of the shuttle. With such arrangements, there exists undesirable friction and required adjustments, as well as poor wear characteristics. Attempts have been made to employ permanent magnets in a shuttle valve assembly to give more positive operation, but typical prior art arrangements do not provide reliable operation over a Wide range of air pressures and pump speeds.

Accordingly, it is a principal object of the present invention to provide a relatively simple and reliable fluid operated hydraulic pump.

It is an additional object of this invention to provide an air operated pump employing an improved shuttle valve assembly for control thereof.

A further object of this invention is to provide an improved shuttle valve assembly.

These and other objects and features of this invention will become more apparent from a consideration of the following description taken in conjunction with the drawings in which:

FIGURE 1 is a simplified schematic diagram of an air operated hydraulic pump according to the present invention;

FIGURE 2 is a cross-sectional view of a pump according to the present invention;

FIGURE 3 is a cross-sectional view taken along a line 33 of FIGURE 2;

FIGURE 4 is a cross-sectional view taken along a line 44 of FIGURE 2; and

FIGURE 5 is a cross-sectional view taken along a line 55 of FIGURE 4.

Turning now to the drawings, an air operated hydraulic pump including an improved shuttle valve assembly is shown in simplified schematic form in FIGURE 1. A cylinder including a cylindrical barrel section 11 and 3,465,686 Patented Sept. 9, 1969 end walls 12 and 13 houses a piston assembly 14 including a pair of pistons 15 and 16. The piston 15 is coupled with an oil plunger 17, and the piston 16 is coupled with an oil plunger 18. The oil plungers 17 and 18 extend into plunger pumps 19 and 20 (note FIGURE 2) equipped with check valves for pumping hydraulic fluid for operating hydraulic equipment, such as, hydraulic presses, hydraulic rams, and the like.

Coupled with the cylinder and piston assembly is a shuttle valve assembly 24 including a valve housing 25 and a shuttle 26. Permanent magnets 27 and 28 are mounted in the housing 25 spaced from but adjacent the ends of the shuttle 26. An air inlet 29 is provided through the housing 25 and communicates with an intermediate chamber 30 of the valve assembly. Air passageways 31 and 32 communicate with the intermediate chamber 30, and extend through the respective end walls 12 and 13 of the cylinder 10 to supply air pressure on the respective pistons 15 and 16. Exhaust ports 33 and 34 also communicate with the intermediate chamber 30. Additionally, a control air passageway 35 in the valve body 25 communicates through passageways 36 and 37 with respective control chambers 38 and 39 at the ends of the assembly. The passageway 35 communicates with the inlet 29 at all times irrespective of the position of the shuttle 26. Orifices or restrictions 41 and 42 are provided in the respective passageways 36 and 37 for purposes which will be described subsequently. The shuttle valve assembly also includes escapement valves 45 and 46 which communicate through respective passageways 47 and 48 with the respective end chambers 38 and 39. The escape ment valve 45 includes a spring biased ball 50 cooperating with a valve seat 51, and the valve 46 includes a spring biased ball 52 cooperating with a valve seat 53. Escapement valve push rods 54 and 55 are provided through the respective end walls 12 and 13 to operate a respective escapement valve 45 or 46 as a push rod is contacted by a respective piston 15 or 16. It will be apparent, that as a rod engages a ball, the escape valve opens thereby venting one of the passageways 47 or 48 to the atmosphere. For example, as shown in FIGURE 1 the piston 16 has engaged the push rod 55 thereby depressing the ball 52 and allowing the passageway 48 to be vented to the atmosphere. This action reduces the pressure in the right-hand end chamber 39 having caused shuttle 26 to move to the right as shown in FIGURE 1.

Turning now to the operation of the pump illustrated in FIGURE 1, it will be seen that air pressure at the inlet 29 is supplied through the intermediate chamber 30 and the passageway 32 to the right-hand side of the piston 16. The left-hand side of the cylinder 10 now is vented through passageway 31, chamber 30 and exhaust port 34. Air pressure also is supplied through the chamber 30 and the passageways 35, 36 and 37 to the end chambers 38 and 39. At this time, the chamber 39 still is ventedto the atmosphere through the passageway 48 and the escapement valve 46. The differential pressure between the chambers 38 and 39 along with the force of the magnet 28 acting on the right-hand end of the shuttle 26 prevent the shuttle 26 from moving from the position shown in FIGURE 1. Air pressure through the passageway 32 into the cylinder 10 causes the piston 16, and hence the piston 15, to move to the left. As the piston 16 moves away from the push rod 55, the escapement valve 46 closes and pressure slowly builds up in the right-hand chamber 39. The rate of pressure buildup is determined by the size of the orifice 42 which is selected to have a smaller airflow capacity than the escapement valve 46.

When the piston 15 contacts the push rod 54, the escapement valve 45 opens thereby venting the left-hand chamber 38 to the atmosphere through the passageway 47. The airflow capacity of the orifice 41 likewise is smaller than the capacity of the escapement valve 45 thereby allowing the pressure in the chamber 38 to drop below the pressure in the chamber 39. This differential pressure between the chambers 38 and 39 causes the shuttle 26 to move to the left as viewed in FIGURE 1, and as the shuttle approaches the magnet 27 additional pull is exerted on the left-hand end of the shuttle 26 to cause a positive action thereof, i.e., the shuttle moves positively to the left without stopping in an intermediate position. An example pressure in each chamber before the valve 45 opens may be twenty pounds per square inch, with the pressure in the chamber 38 dropping to ten pounds per square inch after the valve 45 opens. The particular differential pressure is not critical. When the shuttle moves to the left, air pressure is supplied through the inlet 29, the intermediate chamber 30 and the air passageway 31 into the cylinder 10. The pressure acts on the left-hand side of the piston 15 thereby causing the piston assembly 14 to move to the right as viewed in FIGURE 1. Air in the cylinder 10 between the piston 16 and end wall 13 is exhausted through the passageway 32, the chamber 30 and the exhaust port 33 inasmuch as the shuttle 26 now is in its left-most position. With the foregoing pump, the structural details of which will be described subsequently, the shuttle valve assembly provides reliable operation without stalling in a neutral position. The pump can operate over a large range of speeds, for example, between less than one strOke per minute to over several hundred cycles per minute. Also, the pump operates reliably over a wide range of air pressures, such as approximately eight to ten pounds per square inch to almost as high a pressure as can be accommodated by the struclure of the pump. No adjustments are required in the present pump or shuttle valve assembly to enable the same to operate over a wide range of pressures. Some prior art pumps require a substantial pressure buildup within the cylinder 10 after a piston moves to the limit of travel before shifting of the shuttle will occur; whereas, the present shuttle operation is independent of cylinder pressure.

An exemplary construction of an air operated hydraulic pump and shuttle valve assembly therefore is illustrated in FIGURES 2 through which are substantially to scale. Like reference numerals are used on like components. The end walls 12 and 13 of the cylinder assembly are secured to the barrel section 11, and are sealed therewith by means of respective O-rings 60 and 61. The pistons 15 and 16 are affixed to the respective oil plungers 17 and 18 and need not be coupled together, and rubber seals 62 and 63 are arranged about the peripheries of the respective pistons. The plungers 17 and 18 extend through the end walls 12 and 13 and are air sealed at '64 and 65. The plunger pumps 19 and 20 are affixed to the respective end walls 12 and 13 and are sealed therewith by O-rings 67 and 68 to prevent air from entering the pumps. The balls 50 and 52 of the valves 45 and 46 are spring biased toward the seats 51 and 53, and the valves are closed by plugs. The plunger pumps 19 and 20 are conventional check valve type oil pumps which receive oil which in turn is pumped by the respective plunger to an outlet. Each has an oil inlet 69 and 70, and an oil outlet 71 and 72. The outlets of both pumps typically are coupled together and to an oil cylinder of the hydraulic equipment to be operated by the present hydraulic pump. By employing two plunger pumps in this manner twice the number of oil impulses are provided to give a more even oil flow. Alternatively, each plunger pump may be coupled to identical size cylinders or rams to cause each to move an equal amount. Also, different size plungers may be used to obtain different output oil pressures and volumes. It will be noted that the piston assembly 14 is considerably larger than the plungers 17 and 18 thereby giving a substantial multiplication factor, e.g., one pound per square inch air pressure provides approximately one hundred and twenty-five pounds per square inch oil pressure output.

The shuttle valve housing 24 is formed of a valve body 74, brackets 75 and 76 and escapement housings 77 and 78. As previously discussed in connection with the description of FIGURE 1, the air inlet 29 communicates with an intermediate chamber 30 within the body 74. The chamber 30 is formed by a bore within the body 74, and five grooves 80 through 84. The groove 80 communicates with the exhaust port 33, the groove 81 communicates with the air passageway 32, the groove 82 communicates with the control air passageway 35, the groove 83 communicates with the air passageway 31, and the groove 84 communicates with the exhaust port 34. An exemplary size for the orifices 41 and 42 is sixty-thousandths inch in diameter.

The shuttle 26 is an elongated cylindrical member, which may have a diameter of, for example, seven-eighths inch, and which has heads 86 and 87 at the ends thereof and an intermediate portion which is necked-down at 88 and 89 thereby forming a cylindrical land 90. The heads 86 and 87 may be integral or separate pieces affixed to the remainder of the shuttle. The groove 82 allows air to flow from the inlet 29 to the passageway 35 even when the land 90 of the shuttle 26 is centered with respect to the groove 82. The land 90 is slightly wider than the groove 82 to prevent air pressure in passageways 31 and 32 at the same time. O-rings 94 and 95 are provided in the body 74 about the shuttle 26 to prevent the heads 86 and 87 thereof from contacting the respective magnets 27 and 28 and thereby serve to reduce noise. The various passageways may be formed by drilling and any unnecessary remaining openings may be sealed with screw plugs.

The brackets 75 and 76 are sealed with respect to the body 74 and the escapement housings 77 and 78 by 0- rings 96 through 99 thereby forming the chambers 38 and 39. A seal also is provided for the passageways 36 and 37 by means of O-rings 102 and 103. Seals also are provided for the passageways 31 and 32 by respective O-rings 104 and 105 (note FIGURE 5 and respective O-rings 106 and 107. The magnets 27 and 28 are alike, and they may be cylindrical and press-fit into the respective housings 77 and 78. These magnets may have, for example, approximately a fourteen pound pull. With twenty thousandths of an inch spacing between the heads 86 and 87 of the shuttle 26 and the respective magnets 27 and 28 when the shuttle is at its respective limits of travel, these magnets provide a pull of approximately eight pounds. As noted above, the shuttle operates back and forth as a result of the difference in pressures in the chambers 38 and 39. Each magnet exerts an additional pulling force on the shuttle to ensure that it moves to its limit of travel. This is particularly important when the air pressure to the overall pump device is turned off during movement of the shuttle to prevent the shuttle from stopping in a center position.

The present embodiment of this invention is to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims therefore are intended to be embraced therein.

What is claimed is:

1. A hydraulic pump for delivering a hydraulic fluid under pressure comprising:

reciprocating piston means mounted within a cylinder said piston means being coupled with hydraulic fluid pumping means which supplies said hydraulic fluid under pressure,

shuttle valve means coupled with said cylinder means,

said shuttle valve means including a valve housing having an intermediate chamber for communicating with a fluid inlet, fluid exhaust ports, and outlet fiuid passageways coupled with said cylinder for causing said piston means to move, said valve housing including a pair of control chambers, said valve housing including a control fluid passageway coupling said intermediate chamber with said control chambers, said control fluid passageway having predetermined restrictions therein between said intermediate chamber and said control chambers, said shuttle valve means including a shuttle member mounted within a bore said valve housing for controlling communication from said inlet to said passageways and from said passageways to said ports, and

a pair of escape valve means separately communicating with said respective control chambers for venting the same to the atmosphere as a function of the position of said piston means.

2. A pump as in claim 1 wherein:

said escape valve means having a larger fluid passing capability than said respective restrictions.

3. A pump as in claim 1 wherein:

said intermediate chamber is formed by said bore and a plurality of grooves, said grooves being directly coupled with a respective port or passageway, and

said shuttle member includes neck portions defining an intermediate land.

4. A pump as in claim 1 including:

a pair of permanent magnets respectively mounted in said control chambers always spaced from said shuttle member for exerting additional operating force upon said shuttle member, said shuttle member moving 'back and forth within said bore in said valve housing as a function of diflerential pressure in said control chambers and the pull of said respective magnets for causing fluid to be applied successively on opposite sides of said piston means to cause the same to reciprocate.

5. A pump as in claim 2 including:

a pair of permanent magnets respectively mounted in said control chambers always spaced from said shuttle member for exerting additional operating force upon said shuttle member, said shuttle member moving back and forth within said how in said valve housing as a function of differential pressure in said control chambers and the pull of said respective magnets for causing fluid to be applied successively on opposite sides of said piston means to cause the same to reciprocate.

6. A shuttle valve assembly for supplying a fluid from an inlet thereof successively to a pair of outlets for operating a hydraulic device comprising:

a valve housing having a bore therein,

a shuttle mounted within said bore, said shuttle having enlarged ends thereby defining an intermediate chamber within said valve housing,

said valve housing including a fluid inlet, a pair of fluid outlets and a pair of ports, said shuttle having an intermediate land for controlling fluid flow between said inlet and said respective outlets as a function of the position of said shuttle within said bore,

said valve housing including a pair of control chambers at the ends of said shuttle, a control fluid passageway communicating directly between said intermediate chamber through respective alike fluid restrictions with said respective control chambers, and

a pair of escapement valve means separately coupled der pressure comprising:

reciprocating piston means mounted within a cylinder, said piston means dividing said cylinder into a pair of chambers and said piston means having opposing faces respectively coupled through the respective ends of said cylinder with a pair of hydraulic fluid pumping means which supply hydraulic fluid under pressure,

shuttle valve means coupled with said cylinder means, said shuttle valve means including a valve housing having a fluid inlet and fluid exhaust ports, and having a pair of outlet fluid passageways coupled with said cylinder for supplying a fluid respectively to said chambers of said cylinder for causing said piston means to move, said valve housing including a pair of control chambers and a control fluid passageway for coupling said fluid inlet with said control chambers, said control fluid passageway having predetermined restrictions therein between said fluid inlet and said respective control chambers, and said shuttle valve means including a shuttle member mounted within said housing for allowing communication between said fluid inlet and said control fluid passageway, and for controlling communication between said fluid inlet and said outlet fluid passageways and for controlling communication between said outlet fluid passageways and said exhaust ports to supply a fluid from said fluid inlet alternately to said chambers of said cylinder and to alternately vent said chambers of said cylinder through said exhaust ports, and

a pair of escape valve means having separate passageways respectively communicating with said control chambers for alternately venting said control chambers as a function of the position of said piston means within said cylinder.

9. A pump as in claim 8 wherein:

said piston means comprises a pair of adjacent pistons mounted within said cylinder and which move together, each of said pistons being coupled through respective ends of said cylinder with said respective pair of hydraulic fluid pumping means, said pair of hydraulic fluid pumping means having like pumping capacity.

10. A pump as in claim 8 wherein:

said piston means comprises a pair of adjacent pistons mounted within said cylinder and which move together, each of said pistons being coupled through respective ends of said cylinder with said respective pair of hydraulic fluid pumping means, said hydraulic fluid pumping means having diflerent pumping capacities.

11. A pump as in claim 8 wherein:

each of said escape valve means comprises a normally closed check valve communicating with a respective one of said control chambers, and a control member for opening said check valve upon movement of a respective one of said pistons to near its limit of travel.

References Cited UNITED STATES PATENTS with said respective control chambers for venting 2,311,979 9 7 Presnell 137-112 the same, said escapement valve means having a 2,834,295 5/ 1958 H]arpe 103 49 larger fluid passing capability than said respective 3,019,735 2/1962 M06116? et 103-49 fluid restrictions. 3,070,023 96 Glasgow 103--51 7. A shuttle valve assembly as in claim 6 in l di 3,203,439 965 Beckett 137-102 a pair of permanent magnets respectively mounted in said control chambers always spaced from the ends of said shuttle for exerting a pull on the respective ends of said shuttle, and

said escapement valve means including means responsive to the operation of said hydraulic device.

ROBERT M. WALKER, Primary Examiner US. Cl. X.R. 91--275 

